Measuring instrument

ABSTRACT

A measuring instrument comprising a pole or body portion including a rack recessed in a slot in one edge of the body. The rack is protected by a flexible strip secured at one end to a tensioning spring. A slide block is manually moved along the pole and includes a pinion which meshes with the rack. The flexible strip is diverted around the pinion by two guide pins.

United States Patent [191 Jeannet et al.

[ MEASURING INSTRUMENT [75] Inventors: Jean-PierreJeannet, Lausanne;

Jenn-Pierre Leuba, Renens, both of Switzerland [73] Assignee: Tesa S.A.,Renens, Switzerland.

[22] Filed: May 5, 1971 [2]] Appl. No.: 140,454

301 Foreign Application PrlorityData May 20, 1970 Switzerland 7436/70[52] US. Cl. 33/143 M, 33/125 M, 308/35 [51] Int. Cl. G0lb 5/00 [58]Field of Search 33/143 I, 143 .I,

33/143 K, 143 R, 143 M, 147 T, 147 R, 125 R; 308/35 [56] ReferencesCited UNITED STATES PATENTS 6/1969 Scholl 33/125 M [451 July 3,1973

FOREIGN PATENTS OR APPLICATIONS 466,588 I] 1969 Switzerland 33/ [47 T1,101,096 3/1961 Germany 308/35 Primary Examiner-William D. Martin, Jr.Attorney-James M. Heilman [5 7] ABSTRACT A measuring instrumentcomprising a pole or body portion including a rack recessed in a slot inone edge of the body. The rack is protected by a flexible strip securedat one end to a tensioning spring. A slide block is manually moved alongthe pole and includes a pinion which meshes with the rack. The flexiblestrip is diverted around the pinion by two guide pins.

14 Cliiims, 2 Drawing Figures Pmmnzmms I915 3.742.609

u x a- JEAN'PIERRE JEANNET JEAN-PIERRE LEUBA INVENTORS AT rORNEYMEASURING INSTRUMENT There are a certain number of measuring instrumentssuch as for example sliding calipers or marking gauges wherein a polecarries a rack which measures with one or more gears controlling thedisplacements of indicating means, said gears as well as said indicatingmeans being fixed to a slide block which is movable along said pole.These instruments generally permit a very accurate reading, however,this reading is dependent on the good state of the gearing of the rackwhich can be damaged by shocks or foreign bodies which may be introducedbetween the teeth and those of the guide gears of the indicating means.

An attempt has been made to eliminate this danger by covering the rackwith a rigid profile fixed to the slide block but the protection thusobtained is only relatively effective because as the profile moves withthe slide block the gearing of the rack is only completely protected atone of the end positions of the slide block; whereas at all otherpositions of said slide block the rack remains more or less uncovered.An attempt has also been made to use a flexible strip covering the rack,said strip leaving the slide block to which it is fixed passing alongthe rack and returning to the slide block via the inside of the polethus forming a sort of movable loop with the slide block, and whereofthe ends are fixed to the slide block whilst its central portion moveswithin the pole. The protection of the rack thus obtained is good butthe system is relatively complicated and costly because it necessitatesthe provision of a return mechanism in the pole for the retum'of thestrip, said return being obtained either by machining the pole or bymaking the said pole in several portions which are I assembled insandwich form. Moreover it is necessary for the strip to slideabsolutely freely within the pole and its guidance must be verycarefully effected if no jamming is to take place. Finally it isnecessary to provide an attachment system for the strip to the slideblock permitting the strip to be restretched from time to time becauseif the strip shrinks or expands a little protection is no longerassured, and there is a danger of the strip folding and jamming in thepole.

With the object of removing these disadvantages the present inventionhas for its object a measuring instrument comprising a pole with a rackmeshing with at least one gear controlling the displacements ofindicating means, the gearing and indicating means being fixed to aslide block movable along the pole, and a flexible protective stripcovering the rack characterized in that the protective strip is fixed tothe pole on either side of the ends of the rack and slides in the slideblock where it is separate from the rack close to the gear.

The accompanying drawings show as an example one embodiment of theobject of the invention.

FIG. 1 is a profile view partially'in cross section;

FIG. 2 is a section along the lines A-Aof FIG. 1.

The measuring instrument shown is a sliding caliper comprising a pole 1having at one of its ends measuring tips 2. The body of the pole 1 ishollowed out along its lower face by means of a groove 3 wherein islocated, in known manner, a rack 4.

On pole 1 is engaged a movable slide block 5 carrying measuring tips 6and comprising indicating means 7 which are driven by a series of gears8 meshing with the rack 4. The control of the indicating means 7 can beeffected in any appropriate known manner and is not described.

in groove 3 is placed a flexible strip 9 whereof one end has a loop 10engaged on a pin .11 fixed in one of the endsof groove 3. The otherendof strip 9 is fixed to a tension spring 12 fixed to a pin 13 fixed inthe other end of the groove 3. Strip 9 extends over the gearing of rack4 and its surface opposite to that which is applied to the gearing ofrack 4 is located in the plane of the lower face of pole l.

Strip 9 passes into slide block 5 and the shoulders 14 and 15, whichsupport the latter against the lower face of pole 1, maintain said striptightly applied against the gearing of rack 4 in the groove 3 of pole 1.Within slide block 5 between support shoulders 14 and 15 strip 9 passesover two guide pins 16 and 17 arranged close to the gears 8 and intendedto separate the strip 9 from rack 4 to give free passage to said gears8.

Thus on moving slide block 5 along pole 1 the latter slides along thelower face of the pole and consequently along the strip whilstmaintaining the latter uniformly applied against the rack except betweenshoulders 14 and 15 where said strip is deflected to permit theengagement of the train of gears 8 with the rack 4. The tension spring12 compensates automatically any variation in the length of the stripand prevents any deformation or folding which could take placeaccidentally during the displacement of the slide block. The rack istherefore effectively protected by the strip 9 whatever the position ofthe slide block and the only part of the rack which is not covered bythe strip is always inside the slide block and therefore there is nodanger of the rack undergoing shocks or damage due to the penetration ofdust or foreign bodies between'its gearing and that of the train ofgears.

The sliding caliper described is of simple and ecconomic constructionbecause it does not require delicate machining or any special design ofthe pole or slide block. As the strip is fixed and only runs along thepole surface it is relatively short and there is no need to providereturn mechanisms. The attachment of the strip to the ends of the groovecontaining the rack is simple and its guidance in the slide block onlycauses slightly deformations which can cause neither fatigue norrupture. I

The strip 9 can be of metal, for example steel, or of. a non metallicmaterial, such as for example a plastics material.

The guide pins 16 and 17 can be fixed or rotary and it is possible toreplace them by any other adequate combination of pins or rollersarranged on the same side or on both sides of the strip or even by asupport ramp of appropriate shape.

It is possible to fix the two ends of the strip by means of springs. Inaddition the springs or springs can be replaced by any other elasticattachment means or be eliminated altogether whereby the strip is thenpreferably but not necessarily elastic. It is also possible for the twoends of the strip to be attached in a non-elastic manner providing atleast one elastic tensioning means thereof which could for example belocated in the slide block. v Y

Although the described example is a sliding caliper it is obvious thatthe measuring instrument according to the invention could also be amarking gauge or any other instrument comprising of a rack engaging withone or more gears controlling the displacements of indicating means, thegears and indicating means being fixed to a slide block which is movablealong the pole.

What we claim is:

l. A measuring instrument comprising; a pole for slidably supporting aslide block, said pole formed with a longitudinal slot; a rackpositioned within the slot and secured thereto; at least one pinionrotatably mounted on the slide block and meshing with the rack; aflexible protective strip also positioned within the slot with its endssecured to the pole and covering the rack on both sides of the slideblock; and deflection means inside the block for moving the flexiblestrip away from the rack and around the pinion when the slide block ismoved along the pole.

2. An instrument according to claim 1 wherein said pole has arectangular cross section and said slot is formed in one of the edgesthereof.

3. An instrument according to claim 1 wherein the flexible strip issecured to the pole on both sides of the ends of the rack.

4. An instrument according to claim 1 wherein said flexible strip issecured to the pole at one end and is connected to a resilient spring atthe other end.

5. An instrument according to claim 1 wherein said deflection meansinside the block include two support shoulders slidably engaging theedge of the pole adjoining the slot, said shoulders forming a deflectionmeans for the flexible strip.

6. An instrument according to claim 1 wherein at least one guide pin ispositioned within the slide block adjacent to the pinion for deflectingthe flexible strip around the pinion.

7. An instrument according to claim-1 wherein the deflection of saidflexible strip away from the rack occurs only within the slide blockthereby providing a protective covering over the rack at all times.

8. An instrument according to claim 1 wherein said resilient means iscoupled between one end of the flexible strip and the pole to provide anelastic tension action for automatically compensating for any variationin the length of the strip.

9. A measuring instrument comprising a pole for slidably supporting aslide block, said pole formed with a longitudinal slot; a rackpositioned within the slot and secured thereto; at least one pinionrotatably mounted on the slide block and meshing with the rack; aflexible protective strip also positioned within the slot with its endssecured to the pole on both sides of the ends of the rack and coveringthe rack on both sides of the slide block; resilient means on said stripto subject same to an elastic tension action to automatically compensatefor any variation in the length thereof; and deflection means inside theblock for moving the strip away from the rack and around the pinion whenthe slide block is moved along the pole.

10. An instrument according to claim 9 wherein said strip is secured tothe pole at one end and is connected to a resilient spring at the otherend.

11. An instrument according to claim 9 wherein the strip is connected toa resilient spring at both ends thereof.

12. An instrument according to claim 9 wherein the strip is elastic.

13. An instrument according to claim 9 wherein the strip is subjected tothe action of at least one elastic stretching means.

14. An instrument according to claim 13 wherein the elastic stretchingmeans is located in the slide block.

1. A measuring instrument comprising; a pole for slidably supporting a slide block, said pole formed with a Longitudinal slot; a rack positioned within the slot and secured thereto; at least one pinion rotatably mounted on the slide block and meshing with the rack; a flexible protective strip also positioned within the slot with its ends secured to the pole and covering the rack on both sides of the slide block; and deflection means inside the block for moving the flexible strip away from the rack and around the pinion when the slide block is moved along the pole.
 2. An instrument according to claim 1 wherein said pole has a rectangular cross section and said slot is formed in one of the edges thereof.
 3. An instrument according to claim 1 wherein the flexible strip is secured to the pole on both sides of the ends of the rack.
 4. An instrument according to claim 1 wherein said flexible strip is secured to the pole at one end and is connected to a resilient spring at the other end.
 5. An instrument according to claim 1 wherein said deflection means inside the block include two support shoulders slidably engaging the edge of the pole adjoining the slot, said shoulders forming a deflection means for the flexible strip.
 6. An instrument according to claim 1 wherein at least one guide pin is positioned within the slide block adjacent to the pinion for deflecting the flexible strip around the pinion.
 7. An instrument according to claim 1 wherein the deflection of said flexible strip away from the rack occurs only within the slide block thereby providing a protective covering over the rack at all times.
 8. An instrument according to claim 1 wherein said resilient means is coupled between one end of the flexible strip and the pole to provide an elastic tension action for automatically compensating for any variation in the length of the strip.
 9. A measuring instrument comprising a pole for slidably supporting a slide block, said pole formed with a longitudinal slot; a rack positioned within the slot and secured thereto; at least one pinion rotatably mounted on the slide block and meshing with the rack; a flexible protective strip also positioned within the slot with its ends secured to the pole on both sides of the ends of the rack and covering the rack on both sides of the slide block; resilient means on said strip to subject same to an elastic tension action to automatically compensate for any variation in the length thereof; and deflection means inside the block for moving the strip away from the rack and around the pinion when the slide block is moved along the pole.
 10. An instrument according to claim 9 wherein said strip is secured to the pole at one end and is connected to a resilient spring at the other end.
 11. An instrument according to claim 9 wherein the strip is connected to a resilient spring at both ends thereof.
 12. An instrument according to claim 9 wherein the strip is elastic.
 13. An instrument according to claim 9 wherein the strip is subjected to the action of at least one elastic stretching means.
 14. An instrument according to claim 13 wherein the elastic stretching means is located in the slide block. 